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Consulting Engineers and Geologists Some natural segregation of large rocks occurred during embankment con- struction. It is our understanding that the embankment is a temporary structure and is scheduled to 6e removed in the year 2003. Currently the haul road embankment runs perpendicular to a drainage and could impound water during a short duration thunderstorm. From the information supplied by Seneca Mine II personnel, no ponding of water has occurred during the past 2 years. No debris lines were discernable when field reconnaissance of the site was conducted. From the data supplied by Seneca Coals, Ltd., for the 10 year, 24 hour storm, the maximum water level elevation is 6641.1 feet (2025.5 meters). For the 25 year 24 hour storm, the maximum water level elevation is 6946.8 feet (2118.7 meters). For the 100 year, 24 hour storm, corresponding max- imum water level is at 6953.6 feet (2120.8 meters). Maximum water level at overflow will occur at 6965.0 feet (2124.3 meters). The embankment is approximately 100 feet (30.5 meters) in height at the . maximum section. Slopes vary from 35 degrees on the downstream side to 38 degrees on the upstream side (1.3 to 1.4 horizontal to 1 vertical). At the base of the upstream face of the embankment, large free draining rock (6 inch (15.2 centimeter) diameter plus) has been dumped after partial completion of the roadway embankment in addition to the natural segregated rock from dragline. construction methods. It is our understanding that regrading will be conducted on the downstream side of the embankment to flatten the embankment slopes to approximately 2:1 (horizontal to vertical) over a period of time. SITE GEOLOGY Regional Geology and Localized Geology. Geology in the project area consists of the Williams Fork Formation and the Iles Formation (see Strati- graphic Column, Figure 2). The Williams Fork Formation underlies the subject site and is composed of interbedded sandstone shale and coal. The formation -2-